Interrogator Module Biased Challenge Distribution for Cloning Resistance
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Solution Overview
Problem
Conventional interrogator modules are vulnerable to replay attacks and cloning, as they use fixed challenge values that can be observed and characterized by cloners, making it difficult to authenticate accessories securely.
Innovation Solution
The interrogator module employs a mechanism with multiple challenge-response pairs stored in a biased distribution, which are derived from a common secret using cryptographic functions, and modifies its behavior based on authentication history and frequency, making it difficult for cloners to learn all challenges and increasing the time and cost of cloning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fixed challenge values are used in authentication, then the authentication process is simple and fast, but the system becomes vulnerable to replay attacks and cloning
Solution Approach 1:
The patent implements dynamic challenge selection where the interrogator module randomly selects challenges from a pool of multiple challenge-response pairs stored in memory. This dynamic selection changes with each authentication attempt, preventing cloners from using fixed replay attacks while maintaining efficient authentication processing.
Solution Approach 2:
The system pre-generates and stores multiple challenge-response pairs in the interrogator module's memory before authentication occurs. This preliminary preparation allows the system to quickly select from pre-computed challenges without performing complex cryptographic operations in real-time, thus maintaining fast authentication speed while enhancing security through multiple available challenges.
2Reliability
If multiple challenge-response pairs are stored and randomly selected, then cloning becomes more difficult, but the device complexity increases
Solution Approach 1:
The patent stores multiple copies of challenge-response pairs in the interrogator module's memory. Rather than implementing complex cryptographic computation hardware, the system uses simplified logic to randomly select from pre-stored challenge copies, reducing device complexity while maintaining security through the multiplicity of challenges.
Solution Approach 2:
The system changes the parameter of challenge selection from a single fixed value to multiple randomly selected values from a stored pool. This parameter change allows the use of simpler hardware that can randomly select from pre-computed challenges rather than requiring complex real-time cryptographic generation capabilities.
3Reliability
If challenges are selected according to a biased distribution, then certain challenges are used more frequently making cloning harder, but the loss of information about challenge selection patterns increases
Solution Approach 1:
The patent implements a biased distribution mechanism where challenges that have been used recently are less likely to be selected again, while unused challenges are more likely to be selected. This feedback-based selection adapts to authentication patterns, making it harder for cloners to predict challenge sequences while maintaining a systematic approach to challenge selection.
Data Source
AI summary
Methods, systems, and computer programs for interrogating an authentication device are disclosed. For example, a mobile device can include an interrogator module that interrogates an authentication module in a mobile device accessory, for example, upon installation of the mobile device accessory. In some implementations, challenge-response pairs and a challenge-response distribution are stored in a memory of an interrogator module. The challenge-response distribution defines selection probabilities for the challenge values. In some instances, the interrogator module receives an authentication request from an authentication module, and in response to the authentication request, the interrogator module selects an initial challenge value according to the challenge-response distribution. The interrogator module sends the authentication module an interrogation message that includes the initial challenge value. The interrogator module can modify the challenge-response distribution, for example, based on suspicious behavior.